Wireless receiving apparatus



2&36399 April 1 R s. BUNTING WIRELESS RECEIVING APPARATUS Filed. March50, 1955 3 Sheets-Sheet l g m m m M 0 MW m w z 7 M fl// mm \ww April14-, W36 R. s. BUNTXNG I WIRELESS RECEIVING APPARATUS Filed March 50,1953 I5 Sheets-Sheet 2 April 4, 1936, R. s, BUNTING WIRELESS RECEIVINGAPPARATUS I5 Sheets-Sheet 5 Filed. March 50, 1933 Eh W II ATTOF/VfyPatented Apr. 14, 1936 UNITED STATES PATENT OFFICE signor to The Britishited, London, England Application March 30, 1933,

Radio Corporation Lim- Serial No. 663,602

In Great Britain April 4, 1932 Claims.

In the specification a wireless receiver is described which comprises aseries of inductances corresponding in number to the tuned input orintervalve circuits on the high frequency side of 5 the receiver,hereinafter referred to generally as input circuits and separateassemblages of fixed or semi-fixed condensers arranged in definite banksor groups, the number of such banks or groups corresponding to thenumber of different stations to which the receiver can be tuned, whilethe number of condensers in each group corresponds to the number oftuned stages and switching mechanism whereby each of the saidinductances is simultaneously combined with one or other of saidcondensers to form a predetermined chain or sequence of similarly tunedcircuits.

According to this invention, a step by step adjustable control member isprovided, having a multiplicity of rotary setting positions in one rangeof movement, in which it switches in fixed tuning condenser elementshaving predetermined capacities to tune the input circuit or circuits toselected predetermined Wave lengths, and another range of movementduring which it controls the volume of the output of the apparatuswithout affecting the tuning.

Inductance and condenser elements are connected to form a plurality ofpartially completed circuits tuned to predetermined fixed wave lengthswith a selector switch for completing any of said circuits through theaerial and detecting system of the apparatus, an operating member formoving this selector switch in one direction only, and a variableresistance controlling the valve filament current, rotation of theoperating member in one direction operating the selector switch, androtation thereof in the opposite direction operating the variableresistance without operating the selector switch.

The apparatus comprises a condenser, or a series of condenserscorresponding to the plurality of circuits to be tuned, such condensersor each condenser comprising two sets of fixed plates, one set being allpermanently connected to the input circuit to be tuned and the other setbeing insulated into connected groups of varying surface areas, therotary selector switch being adapted toconnect any one of said groups,or a plurality of selected units of said groups in parallel, into theinput circuit to be tuned, by a step by step rotary movement of theswitch in the same direction, movement of said switch in the reversedirection controlling the output volume of the apparatus withoutaffecting the tuning.

Each inductance may comprise a pair of coils arranged in sequence, oneof the coils of each pair being adapted for short-wave reception byshort circuiting the other coil by the operation of the switchmechanism.

The input circuit or circuits is or are tuned to 5 the wave-length ofthe selected station by rotation of the single controlling knob in onedirection, rotation of the knob in the reverse direction, controllingthe volume of the signals as required.

The single controlling knob may also control the on and off switch tothe source of electrical supply to the apparatus and a gramophonecontrol switch.

The switching mechanism aforesaid comprises a number of spider framesmounted side by side on an operating spindle, the number of radial armsor vanes of each spider depending upon the number of stations to whichthe receiver can be tuned; the arms of each spider are staggeredrelatively to each other and each arm carries a contact member on itsouter end adapted when the spiders are rotated to make contact withcontacts connected to the condenser plates, there being one of suchcontacts to each single fixed plate and each combination of two or morefixed plates.

The invention will be best understood from the following descriptiontaken in conjunction with the accompanying drawings including Figures1-8 which show a wireless receiver tuning ap paratus having an inputcircuit and two intervalve circuits on the high frequency side of thereceiver.

In the drawings- Figure 1 is the plan view of the tuning mechanismconstructed according to the present invention and adapted for theaerial and two intervalve circuits;

Figures 2, 3, and 4 are sectional views looking in the direction of thearrows respectively associated with the lines A-A, B-B, and CC of Figure1.

Figure 5 is an end view looking in the direction of the arrow D, ofFigure 1.

Figure 6 shows the panel indicating arrangements.

Figure 7 shows an arrangement by which a second receiver such as atelevision signal receiving apparatus using a similar condenserarrangement to that shown in Figure 1 may also be controlled by thesingle controlling knob, and

Figure 8 shows the circuit arrangements of the tuning apparatus ofFigure 1.

Referring more particularly to Figure 1 it will be seen that in theexample shown there are three similar sets of stationary condensers I,2, 3 and a fourth set 4 all supported by, but insulated from the frame 5in the usual manner.

In each similar set of condensers l, 2, 3, one set of alternate platesare connected together whilst the other set of alternate plates isdivided into groups consisting of one, two or more plates according tothe capacity desired, the plates of each group being connected togetherso as to give a determined capacity value and each group being connectedto a respective contacting brush 6 supported by, but insulated from thesupport I. The number of similar sets of condensers corresponds with thenumber of input circuits to be simultaneously tuned. Each set ofcondensers is screened ofi by the partitions ll.

With each contacting brush 6 is associated a metal spider 8, having twomore radial arms 9, than the number of wave lengths to which theapparatus is to be tuned. In the present example there are fourteen arms9, capable of tuning to l2 difierent wave lengths. The spiders 8 arearranged parallel to each other and are mounted on and in electricalconnection with a spindle Iii, which is supported in suitable bearings12, I3. It will be noticed that the spindle It does not pass through thecontrol panel 2!].

The radial arms 9 of each spider 8 are staggered so that according tothe angle of rotation of the spindle Iii from its inoperative positiononly certain predetermined arms make contact with the brushes 6 thusonly throwing into circuit a predetermined capacity value. Thecorresponding arms of two or more spiders of each set may be used at onetime to give the desired capacity, thus throwing in parallel two or moregroups of plates.

Each spider arm 9 is provided near its end with a contact M whichcontacts with a brush 6; there being four different sets of condensersthere are four corresponding sets of spiders, three sets being similarand the fourth set associated with the condenser set 4 which will bereferred to later. One spider 8a of each similar set, is insulated fromthe spindle l0, and contacts with a brush 6a in predetermined positionsfor a purpose hereinafter described.

The end of the spindle IE adjacent to the control panel is provided withone or-more toothed wheels IE, it around each of which a chain passes todrive another controlling spindle or switching mechanism as shown inFigure '7 and which will be referred to later. The outermost wheel [6(see also Figure 2) is provided with a pin 11, projecting parallel withthe axis of the wheel.

The controlling knob i8 is mounted on a spindle ii! which is supportedin the panel 23 in the usual way, and carries on its other end a sleeve21 which is rigidly fixed to the spindle l9 and carries a projectingradial pin 22. The contacting brush 23 which contacts with theresistance coil 25 is carried on a collar 23a l-oosely mounted on thespindle 9, a friction washer Zia being interposed between the sleeve .Hand the collar 23a, the outer face of which bears against a springwasher. Thus by rotation of the knob 18 the brush 23 can be caused totravel in either direction with respect to the coil 24.

The pin 22 contacts with the pin I1 and as the controlling knob I8 isturned in one direction (clockwise) the pin 22 pushes the pin H forwardthus causing the spindle ID with its spiders 8 to rotate.

At the other extremity, the spindle I0 is provided with a pawl andratchet mechanism 25 (see Figure 5) which allows the spindle ID torotate in one direction (anti-clockwise) (in Figure 5) only.

The tension of the pawl-controlling spring 25a is so adjusted and theteeth of the ratchet wheel so shaped that the frictional resistance isgreater than the frictional resistance between the friction washer 2 laand the collar 23a. Thus the spindle I0 is held stationary when byrotation of the knob iii the brush 23 is operated for volume control.

The spiders associated with the condenser set 4 are two in number whichare insulated from the spindle l0 and from one another. One set ofplates of the condenser 4, the aerial condenser, are divided into twogroups so as to give two difinite capacity values. One group of platesis connected to a brush 4a and the other group of plates is connected toa brush 41) (see Figure 1). The set connected to 4a give a smallcapacity and is used when greater selectivity is required or when tuningin to a powerful station. The set connected to 4b is of greater capacityquired is not so great, or when tuning in to a weaker station.

The spider arms 1c are so staggered that an armof only one of the setsis in contact with either of the brushes 4a or 41). A brush 4d issupported by, but insulated from, the frame 5 so as to bear on the armsor" both spiders and is connected to the aerial terminal 38 (see Figure4). A Vernier condenser 3% is also provided and this is connecteddirectly to the aerial circuit.

Figure 4 shows more clearly the device for switching on and off theelectrical power supply to the apparatus when the tuner is brought intouse. This comprises a pair of spring iuged contacts 25, 21 one of which23 engages a cam disc 28 on the operating spindle [0, thereby makingcontact which is broken when a recess on the cam disc 28 comes, in thecourse of the rotation of the disc, opposite to the contacts and theyare separated, as shown in Figure 4 thus opening the circuit of theelectrical power supply to the apparatus. The recess in the disc 28 isarranged to come opposite the contacts in the off position of theoperating spindle ii). A similar device to that shown in Figure 4 may beadopted for use as a gramophone control switch, such as a notched discwhich when the controlling knob I8 is set to gramophone position allowscontact members to come together to complete the connections of thewireless receiver system with the electrical pick-up system of thegramophone. The panel indicating arrangements shown in Figures 6 and 7consist of a plate 29 provided at intervals with slots framingtransparent name plates bearing the wave lengths, names of transmittingstations or other indicia of the received signals. Behind this platethere is a rotating arm 30 mounted on a spindle 3| which, as shown inFigure '7 is provided with a driving wheel 32 which is driven by a smallchain or belt from the main spindle Ill. The spindle 3| is supported inbearings on the bracket 33 fixed at the back of the loud speaker bafiie29a. The free end of the arm 30 is provided with a lamp holder andindicating lamp 34. An insulated contact plate rotates in unison withthe spindle 3| and the contacts of the plate are connected up to one ofthe lamp 34 terminals. When the lamp 34 is rotated behind the plate 29the contact on the insulated contact plate completes a circuit to supplythe;

and is used when the selectivity relamp with current, the return of thecircuit being through the spindle 3|. Thus the lamp indicates to whichwave length or transmitting station etc., the tuner is tuned byreflection through the particular transparent name plate.

.Figure 7 also shows how a television signal receiving set 35 may betuned in unison with another signal receiving set by means of the beltor chain coupling 36 driven fromthe operating knob l8 and spindle l0.

- Referring to Figure 8, the coil S. W. alone is used for short wavelengths, the coil L. W. used only for long waves, being cut out .ofaction by a contacting brush 31, which is always in contact with spiders8a, the arms of which in short wave positions contact with brush 6athereby short circuiting the coil L. W. The arms of the spider 8acorresponding to long wave positions do not make contact with brush 6aso that the coil L. W. remains in circuit in series with coil S. W.Similar arrangements are provided for each high frequency stage as wellas for the detector stage D.

It will be understood that the receiver is adjusted in the course ofmanufacture in such a manner that the contacts M on the staggered armsof the spider elements 8 of the switching mechanism contact withpredetermined contact brushes 6 connected to the fixed condenser platesaccording to the capacity required to suit the wave lengths of theseveral stations to which the receiver can be tuned and also the arms ofthe spider element 811 are staggered in a predetermined manner toperform their operation when required.

When it is required to tune in the receiver to one of the stationsindicated on the selector panel, the controlling knob is rotated, say ina clockwise direction, and the pin 22 pushes the pin l'l forward causingthe spindle H] to rotate. Continued rotation of the spindle brings theindicator lamp 34 opposite the name plate of the station required.

The spider elements 8 also having been rotated with the spindle ID, asuccessive set of the arms or vanes 9 thereof are brought into contactwith predetermined contact brushes 6 connected to the first condenserplates to suit the wave length of the station selected. The spiders 40will also have been rotated so as to select the right capacity for theaerial condenser and if the station selected transmits on a short wave,the long wave inductance coils L. W. will be short circuited as alreadyexplained. In the example shown there are fourteen arms equally spacedon each spider element. One corresponds to the off position of theswitch controlling knob when the main circuit is broken at 26, 21, allthe spider arms being then out of contact with brushes 6 and 6a andanother corresponds to the gramophone position of the controlling knob,when the wireless apparatus is connected to the gramophone pick-up unit,as already described, by a switch similar to the switch 26, 21, 28. Thuseach spider has two arms which are, in fact, dummies. The remainingtwelve positions are taken up with twelve stations of definite wavelengths.

When the station has been selected the controlling knob I8 is turned inthe reverse (or anti-clockwise) direction causing the brush arm 23 totravel over and in contact with the resistance element 24, and therebyregulating the volume of the signals as required.

Arrangements may be made to increase the amount of coupling between thevarious tuned circuits by bringing in or cutting. out additionalcondensers which would be governed .by the switching mechanism and isobvious to those skilled in the art.

It is to be understood that the invention does not include within itsscope any multiple variable condenser unit having movable condenserplates, or having fixed plates in combination with a plate selectingswitch, unless the latter also has a range of rotary movement duringwhich it controls the volume output of the apparatus without affectingits tuning.

What I claim is:-

1. Wireless receiving apparatus including a tuning apparatus for inputcircuits, condensers corresponding to a plurality of circuits to betuned, such condensers comprising two sets of fixed plates, one setbeing all permanently connected to an input circuit to be tuned and theother set being insulated into connected groups of varying surfaceareas, in combination with arotary selector, a rotary volume controlmember, an operating member loosely engaging said selector and fixedlycarrying said control member, said selector adapted to connect any oneof said groups, or a plurality of selected units of said groups inparallel into the input circuit to be tuned, by a step by step rotarymovement of the selector, means for effecting rotation of the selectorby rotation of the operating member in one direction only, and means forefiecting rotation of the volume control member alone by rotation of theoperating member in the opposite direction.

2. In a wireless receiving apparatus including a tuning apparatus forinput circuits, condensers corresponding to a plurality of circuits tobe tuned, said condensers comprising two sets of fixed plates, one ofsaid sets being permanently connected to an input circuit to be tuned,the other set of plates being insulated into connected groups of varyingsurface areas, a rotary selector rotatable in one direction only adaptedto connect a plurality of selected units in parallel with the inputcircuits to be tuned, a rotatable operating member loosely engaging saidselector, a controlling member adapted to actuate said operating memberto tune the input circuits with the wave length of the selected stationwhen rotated in one direction, a volume regulating member on saidcontrolling member, means for rotating said selector and control memberwith rotation of said controlling member in one direction, and means forrotating said volume member alone with rotation of said controllingmember in the opposite direction.

3. In a wireless receiving apparatus having an aerial and detectingsystem, inductance and condenser elements connected to form a pluralityof partially completed circuits tuned to predetermined fixed wavelengths, a selector switch for completing any of said circuits throughthe aerial and detecting system of the apparatus, a rotatable operatingmember, means engaging said switch and said member for moving saidselector switch in one direction only, a variable resistance carried bysaid member and controlling the valve filament current, means engagingsaid resistance and said member upon rotation of the member in theopposite direction to effect adjustment of the variable resistanceindependently of the selector switch, said inductance means comprising apair of coils arranged in sequence, and means controlled by saidoperating member for cutting out one of said coils through said switchmechanism.

4. Wireless receiving apparatus including a tuning apparatus for inputcircuits, condensers corresponding to a plurality of circuits to betuned, such condensers comprising two sets of fixed plates, one setbeing all permanently connected to an input circuit to be tuned and theother set being insulated into connected groups of varying surfaceareas, in combination with a rotary selector adapted to connect any oneof said groups, or a plurality of selected units of said groups inparallel into the input circuit to be tuned, by a step by step rotarymovement of the selector, a volume control member, an operatlng memberloosely engaging said selector and fixedly engaging said control member,means for rotating said selector and operating member in one direction,and means for rotating said operating member and said volume controlmember in the reverse direction independently of said selector.

5. Wireless receiving apparatus including a by step rotary movement ofthe member in the same direction, movement of said member in the reversedirection controlling the output volume of the apparatus withoutailecting the tuning, and pawl and ratchet means for holding saidspindle and selector from rotating relative to each other in onedirection.

REGINALD STEWART BUNTING.

